Transfer Unit

ABSTRACT

A transfer unit  10  is structured including a supporting plate  11  having a supporting face  20 A for a semiconductor wafer W, an arm plate  30  for supporting the supporting plate  11  and a parallelism adjuster  14  provided between the supporting plate and the arm plate  13.  The supporting plate is arranged to be able to intake/discharge the air from the supporting face. Owing to the reaction when the supporting plate comes close to the semiconductor wafer W in the blowing state of the air, the supporting plate is maintained to be parallel with respect to the wafer. After coming close to the wafer in the state that the parallelism is maintained, the wafer is sucked and transferred.

TECHNICAL FIELD

The present invention relates to a transfer unit, in particular, to atransfer unit suitable for transferring a fragile plate-like object suchas semiconductor wafer, which is polished to an extremely thin state, bysucking the same without giving any damage.

BACKGROUND ART

For a semiconductor wafer (hereinafter, simply referred to as “wafer”)on which a circuit surface is formed, a series of processing areperformed in a state having a protection tape on the circuit surface,such as sticking a heat sensitive adhesive sheet for die bonding to therear surface side and then mounting to a ring frame. An apparatus forcarrying out such a series of processing is disclosed in, for example, aPatent Document 1.

In the Patent Document 1, as an apparatus for transferring the wafer toeach process, an arm type transfer unit is employed. The transfer unitis structured including a suction portion at the front-end side of thearm. The suction portion is arranged so as to suck a wafer to supportand transfer the wafer to predetermined positions.

[Patent Document 1]

Japanese Patent Application Laid-open No. 2003-257898

DISCLOSURE OF THE INVENTION [Problems to be Solved by the Invention]

However, in the structure disclosed in the Patent Document 1, such anarrangement is simply adopted that the front-end side of the arm ismoved and the suction portion is pressed to the wafer to suck and holdwhen transferring the wafer. Therefore, there reside the followingdisadvantages.

That is, recent wafers are ground to a thickness of, for example,several dozens μm order. Therefore, in the case where an error in theparallelism between the supporting face of a supporting plate and thesurface of the wafer, i.e., a minute inclination is generated, it mayhappen that a partial load is applied to the wafer when the supportingplate comes into contact with the surface of the wafer. Therefore, therearises such a specific disadvantage that the wafer is given a damagesuch as a crack, break or the like by this partial load. Further, it isextremely difficult to assemble the apparatus so that the parallelism ofthe supporting plate with respect to the wafer is maintained with a highprecision. And furthermore, the precision of the component parts usedfor the purpose is strictly required, leading to a considerable costimpact.

[Object of the Invention]

The present invention has been proposed to solve the abovedisadvantages, while taking into consideration an aspect the problemthat error or the like in assembly of the apparatus is unavoidable. Itis an object of the present invention to provide a transfer unit capableof, when supporting a fragile plate-like object such as wafer with asupporting plate, adjusting the parallelism with respect to theplate-like object and creating a state of parallel contact to theplate-like object to support the same, and thereby preventing the damageof the plate-like object.

[Means for Solving the Problem]

In order to achieve the object, the present invention is arranged sothat a transfer unit, including a supporting plate having a supportingface for supporting a plate-like object by sucking it, and holdingmembers for holding the supporting plate, transfers the plate-likeobject to a predetermined position by sucking the plate-like object onthe supporting face of the supporting plate, wherein

the supporting plate is arranged so as to be able to intake and blow outthe air from the supporting face for the plate-like object, and isarranged so that the parallelism to the plate-like object is adjustablevia a predetermined parallelism adjuster, wherein

the parallelism adjuster adjusts the parallelism between the supportingface and the plate-like object by blowing out the air toward theplate-like object from the supporting face of the supporting plate.

Also, the present invention is arranged so that a transfer unit,including a supporting plate having a supporting face for supporting aplate-like object by sucking it, and holding members for holding thesupporting plate, transfers the plate-like object to a predeterminedposition by sucking the plate-like object on the supporting face of thesupporting plate, wherein

the supporting plate is arranged so as to be able to intake and blow outthe air substantially evenly within a plane from the supporting face forthe plate-like object, and is arranged so that the parallelism to theplate-like object is adjustable via a predetermined parallelismadjuster, wherein

the parallelism adjuster is held by the holding members so that theparallelism with respect to the surface of the plate-like object isadjustable by the action of the air blown out from the supporting facewhen coming close to the plate-like object while the air is blown outfrom the supporting face.

In the present invention, the holding members include the supportingplate and an arm plate positioned substantially parallel to thesupporting plate, and the parallelism adjuster is supported in a movablestate in the direction substantially perpendicular to the surface of thearm plate so as not to fall off, and includes a supporting shafts ofwhich one end is fixed to the surface of the side opposite to thesupporting face of the supporting plate and spring members disposedaround the supporting shafts between the supporting plate and the armplate.

Also, the supporting shafts are arranged so as to extend through the armplate, the shafts being capable to be inclined with respect to thesurface of the arm plate.

Further, the supporting plate may be arranged so as to be able to adjustthe temperature via a temperature control device.

Furthermore, the present invention may be arranged so that, by graduallyreducing the blowing pressure of the air, the supporting plate comesslowly into contact with the plate-like object.

Still further, a semiconductor wafer is adopted as the plate-likeobject.

[Advantage of the Invention]

According to the present invention, the air is blown out to theplate-like object like a wafer to adjust the parallelism of thesupporting plate. Therefore, even in a state such that the supportingplate is assembled with an error with respect to the holding member, theerror is corrected and the parallelism between the supporting plate andthe plate-like object is adjusted. Accordingly, there is no disadvantagesuch that, when the supporting plate comes into contact with theplate-like object, a partial stress is given to the plate-like object;thus, damages like a crack can be prevented efficiently.

Moreover, since the air is blown out to the plate-like object, even whenthe plate-like object itself includes a minute warp or deformation, thewarp or deformation can be corrected. In this point also, the cause ofdamage of the plate-like object can be eliminated.

Furthermore, according to the arrangement in which the spring membersare disposed around the supporting shafts for holding the supportingplate with the holding member, after terminating the blowing out theair, the supporting plate is depressed toward the plate-like object sideto achieve the contact therewith. Therefore, the relative movement tocome close to each other immediately before the supporting plate comesinto contact with the plate-like object can be carried out by the springforce. Accordingly, the supporting plate can be brought into contactwith the plate-like object without requiring complicated control ofcylinders or the like.

Still further, the supporting plate is arranged so as to be able toadjust the temperature. Accordingly, when the temperature control of theplate-like object is required, the temperature control can be carriedout while transferring the same, which contributes the time reductionfor temperature control operation.

Still furthermore, when such an arrangement is adopted that the blowingpressure of the air is gradually reduced so that the supporting plateslowly comes into contact with the plate-like object, at a point whenthe supporting plate comes into the plate-like object, the depressingforce by the spring members acts on the supporting plate in a bufferedstate. In this point also, damages to the plate-like object can beprevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing the entire structureof a wafer transfer unit in accordance with an embodiment of the presentinvention.

FIG. 2 is an enlarged sectional view of an essential portion shown inFIG. 1.

FIG. 3 is a side view of the transfer unit.

FIG. 4 is a side view of the transfer unit showing a state immediatelybefore the supporting plate sucks a wafer to support the same.

FIGS. 5(A) to 5(C) are views for illustrating the operation of theembodiment.

EXPLANATION OF REFERENCE NUMERALS

10 transfer unit

11 supporting plate

13 holding member

14 parallelism adjuster

20 lower plate

20A supporting face

20B air intake/discharge holes

30 arm plate

33 supporting shaft

34 coil spring (spring member)

W semiconductor wafer (plate-like object)

T1, T2, T3 table

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings.

FIG. 1 schematically shows the structure of a transfer unit inaccordance with an embodiment of the present invention. Referring toFIG. 1, a transfer unit 10 is structured including a supporting plate 11for a wafer W as a plate-like object, a temperature control device 12that controls the temperature of the supporting plate 11, a holdingmember 13 that holds the supporting plate 11, a parallelism adjuster 14disposed between the supporting plate 11 and the holding member 13, anda shifter 15 that moves the supporting plate 11 in the X andZ-directions in FIG. 1.

Below the supporting plate 11, first to third tables T1, T2 and T3 aredisposed, and the transfer unit 10 is structured so as to transfer thewafer W between the tables T1 to T3. Although detailed description ofthe tables T1 to T3 is omitted, each table is structured including adevice for controlling the temperature of the wafer W to a predeterminedtemperature and a device for shifting the table position in the verticalor horizontal directions, if necessary.

As shown in FIG. 2 to FIG. 4, the supporting plate 11 is structuredincluding a lower plate 20 of a substantially square shape viewed fromthe top and an upper plate 21 of a substantially disk-like shape. Thebottom face side of the lower plate 20 is formed as a supporting face20A for the wafer W. Within the lower plate 20, a path 23 extending insubstantially horizontal direction is formed, and in the midway of thepath 23, many air intake/discharge holes 20B communicating with thesupporting face 20A are formed at regular intervals having substantiallysame sizes. The lower plate 20 may be formed of a porous material. Theboth ends of the path 23 communicate with connecting portions 24 havinga pipe-like shape formed at two points adjacent to the corners on theupper face side of the lower plate 20. To each of the connectingportions 24, one end of a hose 27, which is led out from a branchportion 26 provided to an intake/discharge switching valve V (refer toFIG. 1) using a vacuum ejector, is connected.

The temperature control device 12 is disposed in substantially centralportion of the upper plate 21; and a well-known structure is employedtherefor. The temperature control device 12 is provided with a heatingfunction and cooling function of the supporting plate 11; and isarranged so as to heat/cool down the wafer W sucked by the lower plate11 depending on the necessity.

The holding member 13 includes an arm plate 30 positioned substantiallyparallel to the supporting plate 11. The arm plate 30 is formed in asubstantially square shape at the front-end side (left end side in FIG.1), having through holes 31 (refer to FIG. 2) formed adjacent to eachcorner; and in the central area thereof, a central hole 32 for receivingthe upper portion of the temperature control device 12 is formed havingthe inside diameter thereof slightly larger than the periphery of thetemperature control, device 12.

The parallelism adjuster 14 is structured including supporting shafts33, which are inserted freely within the through holes 31 so as to be inthe direction substantially perpendicular to the surface of the armplate 30, and coil springs 34 as spring members disposed around thesupporting shafts 33 between the supporting plate 11 and the arm plate30. The supporting shaft 33 has a bolt-like shape, and at least on theperiphery surface in the upper end area thereof, male screw portion 33Ais formed. A nut member 36 is screwed with the male screw portion 33A ina state that the male screw portion 33A is inserted through the throughhole 31 from the bottom. Owing to this, the supporting shaft 33 issupported movably in the direction substantially perpendicular to thesurface of the arm plate 30 (vertical direction in FIG. 2) in a statethat the supporting shaft 33 is prevented from falling off. Here, beinginserted freely within the through hole 31, the supporting shaft 33 isallowed to incline with respect to the arm plate 30. The lower end ofthe supporting shaft 33 is fixed to the upper face side of the upperplate 21, which is the side opposite to the supporting face 20A of thelower plate 20. Fixing of the shafts 33 to the plate 21 is achieved inthis embodiment by screwing the male screw 33B, which is formed in thelower end portion of the supporting shaft 33, into the female screwportion 21A, which is formed in the upper plate 21.

The coil springs 34 are provided in a state being interposed between thesupporting plate 11 and the arm plate 30 so as to depress the supportingplate 11 downward. The coil spring 34 is arranged so that compressed toallow the supporting plate 11 to come closer to the arm plate 30 when anupward force is given with respect to the supporting face 20A of thesupporting plate 11.

As shown in FIG. 1, the shifter 15 is structured including a singleshaft robot 40, which is disposed substantially in the horizontaldirection, a cylinder 41, which is provided movably along the extendingdirection (X-direction) of the single shaft robot 40 and extends in thedirection perpendicular to the vertical direction, and a lifting slider42 movably in the Z-direction via the cylinder 41. The base end side(right end side in FIG. 1) of the arm plate is connected to the liftingslider 42.

Next, referring to the drawings including FIG. 5, the transferringmethod of the wafer W in the embodiment will be described.

Here, it is assumed that, as shown FIG. 1, the position where thesupporting plate 11 is positioned above the second table T2 is theinitial position; and that a wafer W set on the second table 2 is suckedand transferred to a first or third table T1 or T3.

As shown in FIG. 3, the supporting plate 11 of the transfer unit 10 ispositioned at a waiting position above the wafer W. When an instructionto suck the wafer W is given from an unshown control device, thecylinder 41 is activated and the lifting slider 42 begins to descend.Owing to the descent of the lifting slider 42, when the suction face 20Ain the lower plate 20 of the supporting plate 11 comes closer to thewafer W, the air intake/discharge switching valve V is driven and theair is blown out from the air intake/discharge holes 20B. Note that theblowing operation of the air may be started at a point of time when thedescent of the lifting slider 42 starts.

Here, assuming that, as show in FIG. 5 (A), due to an attachment errorof the supporting plate 11 with respect to the arm plate 30, a slightinclination of the suction face 20A is generated with respect to avirtual line L parallel to the surface of the wafer W; and that thesupporting plate 11 descends while including a height difference D, thesupporting face 20A comes into contact with a portion of the wafer W(left side in FIG. 5(A)) with the height difference D retained, whichresults in stress concentration.

In this embodiment, as shown in FIG. 5(B), when the supporting face 20Acomes closer to the wafer W; for example, when the supporting face 20Acomes close to the wafer W up to approximately 0.1 mm, owing to thereaction of the discharged air blown out from the air intake/dischargeholes 20B; i.e., the discharged air is reflected at the surface of thewafer W, and generates a force to lift up the supporting plate 11. Whenthe lifting force acts on the supporting plate 11, the supporting plate11 rises against the depressed force of the coil spring 34. Accompanyingthe rising of the supporting plate 11, the supporting shafts 33 changethe inclination within the through holes 31; thus, the supporting face20A is made to coincide with the virtual line L and the parallelism isadjusted.

When the blowing of the air is stopped in this state, owing to thedepressed force of the coil spring 34, the supporting plate 11 comesinto contact with the entire area of the wafer W simultaneously whilemaintaining the parallelism. Then, the intake/discharge operation of theintake/discharge switching valve V is switched to start the intakeoperation of the air through the air intake/discharge holes 20B, thewafer W is sucked and supported by the supporting face 20A. By drivingthe shifter 15 while sucking and supporting the wafer W, the wafer W canbe transferred to the neighboring table T1 or T3. In the case wherethere resides an attachment error in the supporting plate 11 asdescribed above, the supporting face 20A of the supporting plate 11becomes an inclined state with respect to the virtual line L even forthe upper face of the table at the receiving side as well. However, thepressure generated when the supporting plate 11 comes into contact withthe wafer W to suck the same, can be controlled not to be generated.That is, the sucking operation is stopped at a position where thepressurizing force is not applied to the surface of the table at thereceiving side. Therefore, it is not necessary to take the crack or thelike of the wafer W into consideration. Also, such an arrangement may bepossible that, air intake/discharge holes are formed in each surface ofthe tables supporting the wafer W in the same manner as the supportingplate 11; and when receiving the transferred wafer, the air is blown outagainst the wafer W sucked and supported by the supporting plate 11;thus the transfer can be carried out while adjusting the parallelismcausing substantially the same effect as the above-described one.

Therefore, according to the embodiment of the present invention, it ispossible to provide a transfer unit, which takes outstanding effectsnever achieved by the conventional art. That is, in addition to theadvantage that the wafer W can be transferred while eliminating thecauses to damage the wafer W, the temperature of the wafer W can also beadjusted simultaneously while transferring the wafer.

The best structure and method for carrying out the present inventionhave been disclosed so far. However, the present invention is notlimited to the above.

That is, the present invention has been illustrated and described aboutmainly a specific embodiment. However, if necessary, it is possible fora person skilled in the art to add various modifications to theabove-described embodiment with respect to the shape, position ordisposition without departing from the technical spirit and the range ofthe object of the present invention.

For example, in the above embodiment, there has been illustrated anddescribed as the structure in which the transfer unit 10 moves totransfer the wafer W between the tables T1 to T3. However, suchstructure that the table T1 to T3 side moves to transfer the wafer W maybe employed.

Also, the parallelism adjuster 14 in the present invention is notlimited to the structure of this embodiment. For example, it may bearranged in such a way that an air compressor cylinder is providedbetween the supporting plate 11 and the arm plate 30, and the length ofthe cylinder is expanded and compressed by the reaction of thedischarged air blown out from the air intake/discharge holes 20B. Inother words, as for the parallelism adjuster 14 in the presentinvention, it is sufficient to have what can adjust the supporting face20A of the supporting plate 11 to be parallel to the wafer W using theblown out air. Further, the following arrangement is employed in theinvention; i.e., after adjusting the parallelism of the supporting plate11, the blowing of the air from the air intake/discharge hole 20B isstopped, and the supporting plate 11 is allowed to come into contactwith the wafer W by means of the depressed force of the coil spring.However, such a control method may be employed that the blowing out ofthe air is gradually weakened and is terminated finally so that theoperation to bring the supporting plate 11 into contact with the wafer Wcan be carried out slowly.

Further, the object to be sucked is not limited to the wafer W, but afragile plate-like object such as glass may be the object.

1. A transfer unit, including a supporting plate having a supportingface for supporting a plate-like object by sucking it, and holdingmembers for holding the supporting plate, that transfers said plate-likeobject to a predetermined position by sucking the plate-like object onthe supporting face of said supporting plate, wherein said supportingplate is arranged so as to be able to intake and blow out the air fromthe supporting face for said plate-like object, and is arranged so thatthe parallelism to said plate-like object is adjustable via apredetermined parallelism adjuster, wherein said parallelism adjusteradjusts the parallelism between the supporting face and the plate-likeobject by blowing out the air toward said plate-like object from thesupporting face of said supporting plate.
 2. A transfer unit, includinga supporting plate having a supporting face for supporting a plate-likeobject by sucking it, and holding members for holding the supportingplate, that transfers said plate-like object to a predetermined positionby sucking the plate-like object on the supporting face of saidsupporting plate, wherein said supporting plate is arranged so as to beable to intake and blow out the air substantially evenly within a planefrom the supporting face for said plate-like object, and is arranged sothat the parallelism to said plate-like object is adjustable via apredetermined parallelism adjuster, wherein said parallelism adjuster isheld by said holding members so that the parallelism with respect to thesurface of the plate-like object is adjustable by the action of the airblown out from the supporting face when coming close to the plate-likeobject while the air is blown out from said supporting face.
 3. Thetransfer unit according to claims 1 or 2, wherein said holding membersinclude said supporting plate and an arm plate positioned substantiallyparallel to said supporting plate, said parallelism adjuster issupported in a movable state in the direction substantiallyperpendicular to the surface of said arm plate so as not to fall off,and includes supporting shafts of which one end is fixed to the surfaceof the side opposite to the supporting face of said supporting plate andspring members disposed around the supporting shafts between saidsupporting plate and the arm plate.
 4. The transfer unit according toclaim 3, wherein said supporting shafts extend through the arm plate,the shafts being capable to be inclined with respect to the surface ofsaid arm plate.
 5. The transfer unit according to claim 1 or 2, whereinsaid supporting plate is arranged so as to be able to adjust thetemperature via a temperature control device.
 6. The transfer unitaccording to claim 1 or 2, wherein, by gradually reducing said blowingpressure of the air, said supporting plate comes slowly into contactwith said plate-like object.
 7. The transfer unit according to claim 1or 2, wherein said plate-like object is a semiconductor wafer.